17-8
IM DLM3054-01EN
Harmonic Analysis (Harmonics)
You can measure and analyze harmonics.
The harmonics display appears when you select Harmonics.
Harmonics
Harmonics are sine waves whose frequencies are integer multiples of the fundamental wave (normally a 50- or
60-Hz utility frequency sine wave). The input currents that flow through the power rectification circuits, phase
control circuits, and other circuits used in various kinds of electrical equipment generate harmonic currents and
voltages in power lines. When the fundamental wave and harmonic waves are combined, waveforms become
distorted, and interference sometimes occurs in equipment connected to the power line.
The instrument can analyze the harmonics generated by the applicable devices specified in the IEC standards
according to their device class (A to D).
1, 2
To take measurements accurately in accordance with IEC standards,
we recommend that you use a digital power meter from the WT3000 series and harmonic measurement software
(761921), both produced by YOKOGAWA. However, the harmonic analysis features on the DLM series are a
good way of measuring general characteristics.
1 IEC 61000-3-2 Edition 4.0
EN 61000-3-2(2006)
IEC 61000-4-7 Edition 2
2 “Applicable devices” refers to electrical and electronic devices that are connected to low voltage power
distribution systems and that receive 16 A or less of current per cycle. The figure below provides a broad
description of the applicable devices. However, while the instrument can perform harmonic analysis on
single-phase devices, it cannot perform analysis on three-phase devices.
Electrical and electronic equipment having an input
current up to 16 A per phase
• Balanced three-phase
equipment
• Household appliances,
excluding equipment
identified as Class D
• Non-portable tools
(portable tools are Class B)
• Dimmers for incandescent
lamps
• Audio equipment
• Equipment not specified in
one of the other three
classes (B, C, or D)
Class A
• Portable tools
• Arc welding
equipment that is
not professional
equipment
Class B
Class D
Class C
Television receivers, personal
computers (PCs), and PC
monitors with rated power of 600
W or less
Lighting
equipment
Fundamental Wave
The sine wave with the longest period among different sine waves derived from the periodic complex wave or
the sine wave with the fundamental frequency among complex wave components.
Fundamental Frequency
In a periodic complex wave, this is the frequency corresponding to the longest period (the frequency of the
fundamental wave).
Harmonic Order (harmonic order)
The ratio of the harmonic frequency to the fundamental frequency, expressed as an integer.
The instrument can analyze harmonic components up to the 40th harmonic.
Harmonic Component (harmonic component)
The components of waveforms whose frequency is an integer multiple of two or more of the fundamental
frequency.
17 Power Supply Analysis Feature (Power Analysis and Power Measurement, Option)
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